Highlights of CentOS MySQL operations

Highlights of CentOS MySQL operations

How to operate MySQL on CentOS:

1. The problem [root @ rekfan mysql] # service mysql restart occurs.
MySQL server PID file cocould not be found! [Failed]
Starting MySQL... The server quit without updating PID file (/usr/local/mysql/data/rekfan. pid). [failed]

My solution:

The/usr/local/mysql/data/rekfan. pid file has no write permission.
Solution: grant permissions, execute "chown-R mysql: mysql/var/data" "chmod-R 755/usr/local/mysql/data", and then restart mysqld!

Some possible solutions provided on the Internet are as follows:

1. It may be that the/usr/local/mysql/data/rekfan. pid file has no write permission.
Solution: grant permissions, execute "chown-R mysql: mysql/var/data" "chmod-R 755/usr/local/mysql/data", and then restart mysqld!

2. the mysql process may already exist in the process.
Solution: Run "ps-ef | grep mysqld" to check whether the mysqld process exists. If the "kill-9 process number" is used to kill the process and restart mysqld!

3. It may be the second time that mysql is installed on the machine. Residual data affects service startup.
Solution: Go to the mysql data DIRECTORY/data to see, if there is a mysql-bin.index, just remove it, it is the culprit. I am using the third solution!

4. mysql uses/etc/my when the configuration file is not specified at startup. cnf configuration file. Open this file to check whether the data directory (datadir) is specified in [mysqld ).
Solution: Set this line in [mysqld]: datadir =/usr/local/mysql/data

5. skip-federated Field Problems
Solution: Check whether the skip-federated field has been commented out in the/etc/my. cnf file. If so, comment out the field immediately.

6. The error log directory does not exist.
Solution: use the "chown" "chmod" command to grant the mysql owner and permissions.

7. selinux. If it is a centos system, selinux is enabled by default.
Solution: Close it, open/etc/selinux/config, change SELINUX = enforcing to SELINUX = disabled, and then save the disk and restart the machine.

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